Flutter, i.e., self-excited vibrations of turbine blades, in turbine engines can lead to catastrophic failures in turbine components, such as compressors and turbine blades. Flutter is an aero-elastic instability that results from coupling between aerodynamic and inertial forces. This interaction causes unsteady aerodynamic forces acting on the blades leading to vibrations, which in large magnitudes, can cause structural failure. As such, the pressure and flow rate of turbine engines are limited to prevent flutter, which restricts the power output and/or efficiency of turbine engines.
It is well known that rotating disks with blades having identical vibration frequencies are more susceptible to flutter than rotating disks with blades having different vibration frequencies, i.e., intentionally frequency mistuned turbine blades. One known method to vary the vibration frequencies of blades in a rotating disk is to install adjacent blades having non-uniform natural frequencies. Referring to FIG. 1, to prepare blades having different natural frequencies using one known method, a portion of some blades is typically removed from the trailing edge of a turbine blade 10 to create a triangular-shaped void 12 at the airfoil tip of the blade 10. By removing the triangular-shaped void from the trailing edge of the blade 10, the natural frequency of the blade 10 is increased relative to an unmodified blade. Modified turbine blades 10 and unmodified blades are then adjacently installed around a rotating hub to create a rotating disk with improved flutter stability.
However, known methods for changing the natural frequency of turbine blades require the precise removal of material from the blades, which requires expensive machining of the blades, results in wasted raw material, and reduces the efficiency of the turbine engine. Therefore, a new, more economical design for intentionally frequency mistuned turbine blades for more efficient turbine engines is disclosed.